Le second ordre de la politique économique

The policy-mix is modelled using the contributions of modern finance: derivatives, securization, collateral. Debt and equities are European put and call of real assets, which price follows a non-logarithmic stochastic process. The decision of bankruptcy is the exercise of an option, which collateral is the exercise value. Optimal securisation of the public debt for financial intermediaries equalises the marginal costs of bankruptcy according to public debt and real assets. The profits of intermediaries increase the user ?s cost of capital. Monetary policy controls the cost of intermediation with the interest rate, the macroeconomic risk with an intermediate target as the securisation of public debt. Haircuts to refinancing are fixed by a public quotation agency. Coordinated policies are proposed for a monetary area. Haircuts allow to distinguishing between the interventions of the lender of last resort in normal and crisis times. JEL Classification codes: E12, E44, E58.